L10 type (i.e., L one zero type) FeNi (i.e., iron-nickel) ordered alloy is expected to provide magnet material or magnetic storage material without any rare earth or any noble metal. Here, the L10 type ordered structure is a crystal structure having a face-centered cubic lattice as a unit cell in which a Fe layer and a Ni layer are arranged in a <001> direction in a layer manner. Such a L10 type ordered structure is provided by alloy made of FePt, FePd, AuCu or the like. In general, the structure is prepared by heat-treating a disordered alloy at temperature equal to or lower than order-disorder transition temperature Tλ to facilitate diffusion.
However, the transition temperature Tλ, for obtaining the Ll0 type FeNi ordered alloy is 320° C., which is comparatively low temperature. Since the diffusion is extremely slow at the temperature equal to or lower than the transition temperature TX, it is difficult to synthesize only in the heat treatment. Thus, conventionally, various attempts are tried to synthesize the Ll0 type FeNi ordered alloy.
Specifically, conventionally, a method for stacking a single atomic Fe layer and a single atomic Ni layer alternately using a molecular beam epitaxy (i.e., MBE), a method for performing heat treatment in a magnetic field with irradiating a neutron beam, or the like is proposed.